Republican candidate Joe Lhota launched his fiercest attack of the mayoral race Wednesday, charging that when rival Bill de Blasio served under former Mayor David Dinkins in the early 1990s “more people died when he was mayor than anything you can possibly imagine.”

During the first mayoral debate Tuesday night, de Blasio called Lhota’s ex- boss Mayor Rudy Giuliani divisive and said that Lhota “had a ringside seat helping to make that happen.”

Lhota fired back Wednesday on Fox’s “Good Day New York with his harshest rhetoric of the general election.

“Like David Dinkins wasn’t a divisive mayor? The man who crime went to levels that we have never seen before in the City of New York?” said Lhota.

“David Dinkins – more people died when he was mayor than anything you can possibly imagine.”

The city recorded a record 2,245 murders in 1990, Dinkins’ first year.

Last year, there were 419.

Lhota also unleashed a new television ad Wednesday, warning New Yorkers that a de Blasio administration would be soft on crime.

“Bill de Blasio’s reckless agenda on crime will take us back to this …,” the ad tells viewers as pictures of New York in the 1980s with graffiti filled subways and crime tape strewn in the streets flashes across the screen.

The ad ends with video of a recent crazed motorcycle rider using his helmet to smash in the window of an SUV driver on the West Side Highway before a gang of thugs beat the driver as his horrified family watched.

De Blasio has said he wants to go to motorcycle clubs and talk to bikers.

The Democrat also wants to end the NYPD’s use of stop-and-frisk, which has lead to record low crime rates. Lhota wants to keep the controversial practice, but has said that as mayor he would make sure that any cop caught racially profiling is punished.

“If they are convicted of racial profiling, it’s a felony. I don’t know why they haven’t been prosecuted,” Lhota said after the debate Tuesday night.

De Blasio blasted Lhota’s new ad, comparing it to an infamous campaign commercial in the 1988 presidential race.

“It is desperate. It is divisive. It is inappropriate,” de Blasio said.

“A lot of us went through the 1980s, 1990s. We saw the way politics developed sadly for the worst. This is just like the Willy Horton ad. It’s divisive and negative. The images are so far over the top, it’s unbelievable that anybody responsible would ever authorize such a thing. It has no place in our discourse in this city. I think the people are going to be angry and disgusted by this ad.”

Willie Horton was a convicted criminal in Massachusetts who twice raped a woman when he was out of a weekend furlough. George H. W. Bush cited the case in his run for president against Michael Dukakis, who was the state’s governor at the time of Horton’s release.